Biology Definitions

The ability of a system or living organism to adjust its internal environment to maintain a stable equilibrium. 

Directional resposnes by plants to stimuli form environment.

Include:  Phototropism and Geotropism

Sum of physical and chemical processes occurring within a living organism

Moment a pollen grain, released from anther lands on stigma of (normally) another flower. 

Moment the nuclei of pollen grain and ovule fuse together

Series of changed in endometrium in preparation for possible implantation of a fertilized ovum.

The uterus lining breaks down and eventually passes out through the vagina

Feotus' kidneys are not yet functioning and so foetus is unable to excrete all toxins which will poison the body if not removed.

Transfer from mother's blood in placenta via membranes separating blood of mother and foetus and transfer into chronic villi and then into the umbilical vein to foetus along with oxygenated blood. 

An allele that is always expressed if present in an individual

An allele that will only be expressed if there are no other versions of the gene present

An individual who has two copies of the same allele

An individual who has more than one different allele present

A condition in which both alleles of a gene pair in a heterzygote are fully expressed. 

• Interphase
• Prophase
• Metaphase
• Anaphase 
• Telophase

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Is the change in the DNA of a cell.

The gradual change in the range of organisms on the Earth

The mechanism by which new species arise through evolutionary changes

By carefully controlling which examples of a species are allowed to mate, humans are able to rapidly change the average phenotype to obtain only those individuals with desirable features.